Scientific American Mind - September 4, 2008
High-Aptitude Minds: The Neurological Roots of Genius Researchers are finding clues to the basis of brilliance in the brain
By Christian Hoppe and Jelena Stojanovic
Smarter brains tend to be bigger—at least in certain locations.
Researchers have fingered parts of the parietal and frontal lobes as
well as a structure called the anterior cingulate as important for
superior cognition.
Some studies suggest that the brains of brighter people use less
energy to solve certain problems than those of people with lower
aptitudes do. But under certain circumstances, scientists have also
observed higher neuronal power consumption in individuals with
superior mental capacities.
People often overestimate the importance of intellectual ability.
Practice and perseverance contribute more to accomplishment than
being smart does.
Bart Coenders/iStockPhot o
Within hours of his demise in 1955, Albert Einstein’s brain was
salvaged, sliced into 240 pieces and stored in jars for safekeeping.
Since then, researchers have weighed, measured and otherwise
inspected these biological specimens of genius in hopes of uncovering
clues to Einstein’s spectacular intellect.
Their cerebral explorations are part of a century-long effort to
uncover the neural basis of high intelligence or, in children,
giftedness. Traditionally, 2 to 5 percent of kids qualify as gifted,
with the top 2 percent scoring above 130 on an intelligence quotient
(IQ) test. (The statistical average is 100. See the box on the
opposite page.) A high IQ increases the probability of success in
various academic areas. Children who are good at reading, writing or
math also tend to be facile at the other two areas and to grow into
adults who are skilled at diverse intellectual tasks [see "Solving
the IQ Puzzle," by James R. Flynn; Scientific American Mind,
October/November 2007].
Most studies show that smarter brains are typically bigger—at least
in certain locations. Part of Einstein’s parietal lobe (at the top of
the head, behind the ears) was 15 percent wider than the same region
was in 35 men of normal cognitive ability, according to a 1999 study
by researchers at McMaster University in Ontario. This area is
thought to be critical for visual and mathematical thinking. It is
also within the constellation of brain regions fingered as important
for superior cognition. These neural territories include parts of the
parietal and frontal lobes as well as a structure called the anterior
cingulate.
But the functional consequences of such enlargement are
controversial. In 1883 English anthropologist and polymath Sir
Francis Galton dubbed intelligence an inherited feature of an
efficiently functioning central nervous system. Since then,
neuroscientists have garnered support for this efficiency hypothesis
using modern neuroimaging techniques. They found that the brains of
brighter people use less energy to solve certain problems than those
of people with lower aptitudes do.
In other cases, scientists have observed higher neuronal power
consumption in individuals with superior mental capacities. Musical
prodigies may also sport an unusually energetic brain [see box on
page 67]. That flurry of activity may occur when a task is unusually
challenging, some researchers speculate, whereas a gifted mind might
be more efficient only when it is pondering a relatively painless
puzzle.
Despite the quest to unravel the roots of high IQ, researchers say
that people often overestimate the significance of intellectual
ability [see "Coaching the Gifted Child," by Christian Fischer].
Studies show that practice and perseverance contribute more to
accomplishment than being smart does.
Size Matters
In humans, brain size correlates, albeit somewhat weakly, with
intelligence, at least when researchers control for a person’s sex
(male brains are bigger) and age (older brains are smaller). Many
modern studies have linked a larger brain, as measured by magnetic
resonance imaging, to higher intellect, with total brain volume
accounting for about 16 percent of the variance in IQ. But, as
Einstein’s brain illustrates, the size of some brain areas may matter
for intelligence much more than that of others does.
In 2004 psychologist Richard J. Haier of the University of
California, Irvine, and his colleagues reported evidence to support
the notion that discrete brain regions mediate scholarly aptitude.
Studying the brains of 47 adults, Haier’s team found an association
between the amount of gray matter (tissue containing the cell bodies
of neurons) and higher IQ in 10 discrete regions, including three in
the frontal lobe and two in the parietal lobe just behind it. Other
scientists have also seen more white matter, which is made up of
nerve axons (or fibers), in these same regions among people with
higher IQs. The results point to a widely distributed—but discrete—
neural basis of intelligence.
The neural hubs of general intelligence may change with age. Among
the younger adults in Haier’s study—his subjects ranged in age from
18 to 84—IQ correlated with the size of brain regions near a central
structure called the cingulate, which participates in various
cognitive and emotional tasks. That result jibed with the findings,
published a year earlier, of pediatric neurologist Marko Wilke, then
at Cincinnati Children’s Hospital Medical Center, and his colleagues.
In its survey of 146 children ages five to 18 with a range of IQs,
the Cincinnati group discovered a strong connection between IQ and
gray matter volume in the cingulate but not in any other brain
structure the researchers examined.
Scientists have identified other shifting neural patterns that could
signal high IQ. In a 2006 study child psychiatrist Philip Shaw of the
National Institute of Mental Health and his colleagues scanned the
brains of 307 children of varying intelligence multiple times to
determine the thickness of their cerebral cortex, the brain’s
exterior part. They discovered that academic prodigies younger than
eight had an unusually thin cerebral cortex, which then thickened
rapidly so that by late childhood it was chunkier than that of less
clever kids. Consistent with other studies, that pattern was
particularly pronounced in the frontal brain regions that govern
rational thought processes.
The brain structures responsible for high IQ may vary by sex as well
as by age. A recent study by Haier, for example, suggests that men
and women achieve similar results on IQ tests with the aid of
different brain regions. Thus, more than one type of brain
architecture may underlie high aptitude.
Low Effort Required
Meanwhile researchers are debating the functional consequences of
these structural findings. Over the years brain scientists have
garnered evidence supporting the idea that high intelligence stems
from faster information processing in the brain. Underlying such
speed, some psychologists argue, is unusually efficient neural
circuitry in the brains of gifted individuals.
Experimental psychologist Werner Krause, formerly at the University
of Jena in Germany, for example, has proposed that the highly gifted
solve puzzles more elegantly than other people do: they rapidly
identify the key information in them and the best way to solve them.
Such people thereby make optimal use of the brain’s limited working
memory, the short-term buffer that holds items just long enough for
the mind to process them.
Starting in the late 1980s, Haier and his colleagues have gathered
data that buttress this so-called efficiency hypothesis. The
researchers used positron-emission tomography, which measures glucose
metabolism of cells, to scan the brains of eight young men while they
performed a nonverbal abstract reasoning task for half an hour. They
found that the better an individual’s performance on the task, the
lower the metabolic rate in widespread areas of the brain, supporting
the notion that efficient neural processing may underlie brilliance.
And in the 1990s the same group observed the flip side of this
phenomenon: higher glucose metabolism in the brains of a small group
of subjects who had below-average IQs, suggesting that slower minds
operate less economically.
More recently, in 2004 psychologist Aljoscha Neubauer of the
University of Graz in Austria and his colleagues linked aptitude to
diminished cortical activity after learning. The researchers used
electroencephalogra phy (EEG), a technique that detects electrical
brain activity at precise time points using an array of electrodes
affixed to the scalp, to monitor the brains of 27 individuals while
they took two reasoning tests, one of them given before test-related
training and the other after it. During the second test, frontal
brain regions—many of which are involved in higher-order cognitive
skills—were less active in the more intelligent individuals than in
the less astute subjects. In fact, the higher a subject’s mental
ability, the bigger the dip in cortical activation between the
pretraining and posttraining tests, suggesting that the brains of
brighter individuals streamline the processing of new information
faster than those of their less intelligent counterparts do.
The cerebrums of smart kids may also be more efficient at rest,
according to a 2006 study by psychologist Joel Alexander of Western
Oregon University and his colleagues. Using EEG, Alexander’s team
found that resting eight- to 12-hertz alpha brain waves were
significantly more powerful in 30 adolescents of average ability than
they were in 30 gifted adolescents, whose alpha-wave signal resembled
those of older, college-age students. The results suggest that gifted
kids’ brains use relatively little energy while idle and in this
respect resemble more developmentally advanced human brains.
Some researchers speculate that greater energy efficiency in the
brains of gifted individuals could arise from increased gray matter,
which might provide more resources for data processing, lessening the
strain on the brain. But others, such as economist Edward Miller,
formerly of the University of New Orleans, have proposed that the
efficiency boost could also result from thicker myelin, the substance
that insulates nerves and ensures rapid conduction of nerve signals.
No one knows if the brains of the quick-witted generally contain more
myelin, although Einstein’s might have. Scientists probing Einstein’s
brain in the 1980s discovered an unusual number of glia, the cells
that make up myelin, relative to neurons in one area of his parietal
cortex.
Hardworking Minds
And yet gifted brains are not always in a state of relative calm. In
some situations, they appear to be more energetic, not less, than
those of people of more ordinary intellect. What is more, the energy-
gobbling brain areas roughly correspond to those boasting more gray
matter, suggesting that the gifted may simply be endowed with more
brainpower in this intelligence network.
In a 2003 trial psychologist Jeremy Gray, then at Washington
University in St. Louis, and his colleagues scanned the brains of 48
individuals using functional MRI, which detects neural activity by
tracking the flow of oxygenated blood in brain tissue, while the
subjects completed hard tasks that taxed working memory. The
researchers saw higher levels of activity in prefrontal and parietal
brain regions in the participants who had received high scores on an
intelligence test, as compared with low scorers.
In a 2005 study a team led by neuroscientist Michael O’Boyle of Texas
Tech University found a similar brain activity pattern in young male
math geniuses. The researchers used fMRI to map the brains of
mathematically gifted adolescents while they mentally rotated objects
to try to match them to a target item. Compared with adolescent boys
of average math ability, the brains of the mathematically talented
boys were more metabolically active—and that activity was
concentrated in the parietal lobes, the frontal cortex and the
anterior cingulate.
A year later biologist Kun Ho Lee of Seoul National University in
Korea similarly linked elevated activity in a frontoparietal neural
network to superior intellect. Lee and his co-workers measured brain
activity in 18 gifted adolescents and 18 less intelligent young
people while they performed difficult reasoning tasks. These tasks,
once again, excited activity in areas of the frontal and parietal
lobes, including the anterior cingulate, and this neural commotion
was significantly more intense in the gifted individuals’ brains.
No one is sure why some experiments indicate that a bright brain is a
hardworking one, whereas others suggest it is one that can afford to
relax. Some, such as Haier—who has found higher brain metabolic rates
in more astute individuals in some of his studies but not in others—
speculate one reason could relate to the difficulty of the tasks.
When a problem is very complex, even a gifted person’s brain has to
work to solve it. The brain’s relatively high metabolic rate in this
instance might reflect greater engagement with the task. If that task
was out of reach for someone of average intellect, that person’s
brain might be relatively inactive because of an inability to tackle
the problem. And yet a bright individual’s brain might nonetheless
solve a less difficult problem efficiently and with little effort as
compared with someone who has a lower IQ.
Perfection from Practice
Whatever the neurological roots of genius, being brilliant only
increases the probability of success; it does not ensure
accomplishment in any endeavor. Even for academic achievement, IQ is
not as important as self-discipline and a willingness to work hard.
University of Pennsylvania psychologists Angela Duckworth and Martin
Seligman examined final grades of 164 eighth-grade students, along
with their admission to (or rejection from) a prestigious high
school. By such measures, the researchers determined that scholarly
success was more than twice as dependent on assessments of self-
discipline as on IQ. What is more, they reported in 2005, students
with more self-discipline— a willingness to sacrifice short-term
pleasure for long-term gain—were more likely than those lacking this
skill to improve their grades during the school year. A high IQ, on
the other hand, did not predict a climb in grades.
A 2007 study by Neubauer’s team of 90 adult tournament chess players
similarly shows that practice and experience are more important to
expertise than general intelligence is, although the latter is
related to chess-playing ability. Even Einstein’s spectacular success
as a mathematician and a physicist cannot be attributed to
intellectual prowess alone. His education, dedication to the problem
of relativity, willingness to take risks, and support from family and
friends probably helped to push him ahead of any contemporaries with
comparable cognitive gifts.
Note: This article was originally published with the title, “High-
Aptitude Minds”.
Further Reading
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Source: Scientific American
http://www.sciam. com/article. cfm?id=high- aptitude- minds&sc= WR_20080805
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